They are for sure and certain blanks---those used in theatrics, and originally known as "Five in Ones"--in recognition of the fact they'd fit and function in five different weapons---two Colt revolvers, and three Winchester rifles (in 45 Colt, 38-40, and 44-40).

Nowadays they've been fiddled with so as to fit more/different calibers/weapons (the 44's and 410), but they're still called "Five in One's"---so the good old days live on---at least somewhere.

Ralph Tremaine